/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.ignite.internal.cache.query.index.sorted.keys;

import org.apache.ignite.internal.cache.query.index.sorted.IndexKeyType;

/**
 * Represents null value stored in index row or query.
 */
public class NullIndexKey implements IndexKey {
    /** Instance. */
    public static final NullIndexKey INSTANCE = new NullIndexKey();

    /** Private constructor. */
    private NullIndexKey() {}

    /** {@inheritDoc} */
    @Override public int compare(IndexKey o) {
        return o == INSTANCE ? 0 : -1;
    }

    /** {@inheritDoc} */
    @Override public Object key() {
        return null;
    }

    /** {@inheritDoc} */
    @Override public IndexKeyType type() {
        return IndexKeyType.NULL;
    }

    /** {@inheritDoc} */
    @Override public String toString() {
        return "null";
    }
}
